fix: editor usability and visual polish from UI scan

- Rule name is now an inline text field at the top of the editor; the
  pencil/rename button and alert are gone (it was unclear what the edit
  button did). Names are sanitized on commit: trimmed, falling back to
  the kind's default when emptied
- Day-of-week toggles fill the full row width with equal cells and
  >= 44pt tap targets
- 'Add Rule' commit button sits on a bar-material bottom inset so form
  content no longer collides with it while scrolling (found via
  computer-use scan; verified clean in a follow-up scan)
- Tests: 95 passing — new specs for the inline rename flow, day-toggle
  geometry, and name sanitization; three tests now scroll to reach
  bottom-of-form controls, matching real user behavior
- Spec §6 updated for the editor changes

Co-Authored-By: Claude <noreply@anthropic.com>

Severed/Models/RuleDraft.swift

@@ -83,6 +83,15 @@ struct RuleDraft: Hashable {
         return rule
     }
 
+    /// Trims the name and falls back to the kind's default when it is empty,
+    /// so a cleared name field can never produce an unnamed rule.
+    func sanitized() -> RuleDraft {
+        var copy = self
+        let trimmed = name.trimmingCharacters(in: .whitespaces)
+        copy.name = trimmed.isEmpty ? kind.defaultRuleName : trimmed
+        return copy
+    }
+
     var schedule: RuleSchedule {
         RuleSchedule(startMinutes: startMinutes, endMinutes: endMinutes, days: days)
     }